Adhesive and process of making same.



CHARLES H. CAMPBELL, OF CHICAGO, ILLINOIS, ASSIG'NOR TO AMERICAN GLUE CUBI- PANY, OF BOSTON, MASSACHUSETTS.

ADHESIVE AND PROCESS OF MAKIN G SAME.

No Drawing.

T 0 all whom it may concern: 7

Be it known that I, CHARLES H. CAMPBELL, of Chicago, in the county of Cook and State of Illinois, a citizen of the United States, have invented a new and useful Improvement in Adhesives and Processes of Making Same, of which the following is a full, clear, and exact description.

The object of my invention is to provide an animal glue soluble in cold water or water of ordinary temperature.

Various expedients have been resorted to for making a cold-water-soluble animal glue or an animalglue soluble in water of ordinary temperature. Ordinary animal glu posesses a jelly-forming property and alsan adhesive strength. For making the glue soluble in water of ordinary temperature the purpose has been to employan expedient or agent which will destroy the jelly-forming,

property of the glue. The difiiculties with these expedients have been that they have weakened the relative adhesive strength of the glue either by destroying or weakening such strength through chemical reaction upon the glue or by adulterating the glue by reason of the relatively large amount'of the agent used. They, also, have the effect of so destroying the jelly-forming property of the glue that when the glue is dissolved it possesses so little body, or in other words, the glue is of such watery consistency, as entirely unsuits it for many purposes.

It is accordingly the further object of my invention to provide a soluble glue possessing a high adhesive strength and in which, also, the jelly-forming property of the glue is not entirely destroyed so that when the glue is dissolved in cold water or water of ordinary temperature it will possess a certain amount of body and will not be of so watery a consistency as will unsuit it for many uses.

The process is as follows: The glue is first treated with a suitable salt of nitric acid and preferably the ordinary chemical commodity potassium nitrate, KNO although I have found that other salts of nitric acid may be employed with gratifying results- Of the salts of nitric acid suitable for the purpose I find that there need be employed for effecting the desired purpose from three to five Specification of Letters Patent.

Patented May 23, 1916.

Application filed October 12, 1912. Serial No. 725,432.

- per cent. by weight of the salt of nitric acid used or of the potassium nitrate, to one hundred per cent. by weight of the dry glue. In other words, such amount of the salt is employed as will not injure the adhesive strength of the glue by adulteration or wholly destroy its jelly-forming property. A larger percentage of the agent may be used without chemically injuring the adhesive strength of the glue if by chance a larger amount of the agent be used than is necessary. It will, however, tend to undulv lIlJllIe the adhesive strength of the glue by adulteration and to destroy its jelly-forming property which I desire to retain in part. The agent is preferably added to the glue liquor (while Warm) d1 ing the making of the glue and before drying, there being added to the glue liquor three to five per cent. of the agent calculated upon a basis of the dry glue present in the glue liquor. The agent will enter into solution by reason of the water in the glue liquor and will readily act upon the glue, this being preferably fa- 'glue must first be dissolved in the ordinary manner by soaking in water and subsequently heating until the glue has been reduced to a liquid form when the agent is added as before.

According to the process thus far described, the addition of the salt renders the glue soluble in cold water or water of ordinary temperature, but not imparting to it the degree of solubility I desire to obtain if the lesser percentages (three to five per cent. or thereabout) of the salt are employed and tending to adulterate the glue and to wholly destroy its jelly-forming property if larger percentages are used. These difiiculties are overcome, however, by the further continuation of the process. After the lesser percentages of the salt (three to five per cent. or thereabout) have been added to the glue liquor as aforesaid, heat is applied and this preferably during the drying of the glue liquor by the application thereto of artificial heat. I prefer that the degree of heat shall be high and continued for a short Period of time, but not so high or continued for so best results are obtained by a quick roller drying of the glue liquor in thin films at a temperature of approximately 250 F. for a short period of time, usually in practice about one and one half minutes. may, however, be applied at lower temperatures, for example, 160 to 180 F. preferably for a period of time ranging from ten to fifteen minutes or even at a lower tempera ture as from 100 to 120 F. continued for a long period of time, ranging from eighteen to thirty hours, though in neither of these latter cases does one obtain the results obtained from a high degree of heat applied for a short period of time as aforesaid.

The application of the heat to the glue liquor in all cases tends to further but not wholly destroy the jelly-forming property [of the glue it is ground fine, though this is suits it for all purposes of use instead of being of a thin watery consistency as is ordia preferred step for lessening the time in which the glue will become dissolved in cold water or water of ordlnary temperature.

A soluble glue made according to the aforesaid process possesses not only a ready solubility but an adhesive strength greater than its normal strength. It also possesses a body after it has become dissolved which narily obtained in a soluble glue.

What I claimas my invention is: 1. The process of treating animalglue for the purpose of rendering the same soluble at ordinary temperature consisting in treating glue liquor with a suitable salt of nitric acid and subsequently drying. the same in the presence of'app'lied heat.

.2. A process of making glue soluble at ordinary temperatures which'comprises adding a small amount of a substantially neutral, watersoluble nitrate thereto and thereafter applying heat to the dissolved glue in the presence of said nitrate, the amount of heat being substantially equivalent to heatheat in amount sufficient to further lessen the jelly-forming property of the glue, and

to dry the mass, but insufficient to. materially injure the adhesive strength thereof.

4. A process of making glue soluble at OI"? dinary temperature-which comprises treating glue liquor with an agent, capable in The heat 1 its'elf'of only partially destroying "the jelly-' the'mixture to such high degree of heat for v6E forming property of theglue, and subjecting i a relatively short period of time ass-will further lessen the j elly-forming-property of the glue, and will dryjthe' glue, but without causing material injury to the adhesive itself-of only partially destroying the jellyforming property of the glue, and afterward drying the mixture by heat applied thereto in amount suflicient to further lessen the jelly-forming property of the glue without materially injuring the adhesive strength thereof. r V

6. A process of making glue soluble at ordinary temperature which comprisestreating glue liquor with {an agent, capable in itself of only partially destroying the jelly- V forming property of the glue, and afterward drying the mixture by heat appliedthereto at such high temperature for a relatively short period of time as willfurther lessen the j elly-forming property of the glue without materially injuring the adhesive strength thereof.

7. A process of treating glue which comr prises adding to glue liquor a substantially neutral, water-soluble nitrate capable of par: tially destroying the jelly-forming property of the glue, and subsequently drying the same by heat applied thereto. V V f 18. A process of treating glue which comprises heating the gluewith not appreciably more than 5% of a soluble nitrate incapable of injuringits adhesive strength, to at least the boiling point of water.

. 1 9. A process-which comprises treatingdissolved glue with a soluble nitrate free from strong acid, and thereafter drying the glue. i

10. A process which comprises; heating dissolved glue with from 3% to 5% of a soluble nitrate. V r

1 1. A process which comprises, drying dis solved glue withabout- 3 to 5% of'a soluble nitrate free from strong acid.

12. A process which comprises heating dissolved glue with a 'relatively small for a length of time sufficient to substan= tially'dry the mass.

comprises treating 14. A process which dissolved glue with a nitrate of an alkali,

and thereafter drying. the glue. I

15. A process which comprises heating nitrate of an alkali.

dissolved glue with from 3% to 5% of a' soluble nitrate.

18. A dry adhesive comprising glue and a relatively small amount of a nitrate of an alkali.

19. A dry Adhesive comprising about 100 parts of glue and about 3 to 5 parts of an 10 zilkali metal nitrate.

20. As an adhesive, a dry, intimate mix ture of glue and a soluble nitrate.

CHARLES H. CAMPBELL.

\Vitnesses 3 JOHN E. R. HAYES, M. E. FLAHERTY. 

